1. Field of the Invention
This invention relates generally to photographic apparatus having exposure control means responsive to fill-in flash mode of operation and, more particularly, to an exposure control system for photographic apparatus wherein the control system is selectively responsive to the energization of a source of artificial illumination in a "fill-in flash" mode of operation where the ambient scene light intensity levels are relatively high, but portions of the photographic subject are relatively dark.
2. Description of the Prior Art
When taking a photograph under conditions at which the levels of ambient scene light intensity are relatively high, but portions of the photographic subject are relatively dark, it may be desirable to provide additional scene illumination from a source of artificial illumination such as a flashlamp or from an electronic flash device sometimes referred to as a strobe unit. Situations where a source of artificial illumination are used in relatively high ambient light levels are commonly referred to as fill-in flash mode of operation as more fully described in a U.S. Pat. No. 3,610,122 entitled "Shutter Timing System" issued Oct. 5, 1971, by C. H. Biber and assigned in common herewith. Automatic photographic exposure control systems of the type typically configured to combine a light sensitive timing network and a voltage sensitive triggerng circuit, or the like, in controlling relationship with a shutter assembly may also be utilized in photographic situations requiring a fill-in flash form of illumination. Such automatic exposure control systems are capable of providing full control over the regulations of a fill-in flash exposure interval and must also be compatible for operation with artificial illumination under scene conditions representing relatively low ambient light levels.
An artificial illumination control system as is fully described in an application for U.S. Pat. Ser. No. 619,384 by E. Shenk filed concurrently herewith, is provided for a photographic camera for operation in a manner whereby under extremely low levels of ambient scene light intensity, the control system initiates the energization of a source of artificial illumination at a predetermined time period subsequent to the initiation of the exposure interval. Conversely, under conditions of substantially high levels of ambient scene light intensity, the control system initiates the energization of the source of artificial illumination as a consequence of the time integration of the scene light intensity incident to a photoresponsive element reaching a predetermined value. Thus, the artificial illumination control system is automatically operated in both a normal flashmode and a fill-in flash mode depending upon the level of ambient scene liht intensity.
An exposure control system compatible for use with the above-described aritifical illumination control system should be capable of selectively determining exposure interval as a function of whether the camera apparatus is operated in the fill-in flash mode of operation where levels of ambient scene light intensity are relatively high or the ordinary flashmode of operation where levels of scene light instensity are relatively low.
Therefore, it is a primary object of this invention to provide an exposure control system compatible for use in a photographic apparatus of the type having an artificial illumination control system which operates automatically in either a normal flashmode of operation or a fill-in flash mode of operation depending upon the levels of ambient scene light intensity.
It is a further object of this invention to provide an exposure control system for selectively determining exposure interval in response to a camera apparatus being operated in a fill-in flash mode of operation.
It is also an object of this invention to provide an exposure control system for determining a select exposure interval as a function of the energization of a source of artificial illumination as a consequence of the time integration of the scene light intensity incident to a photo-responsive element reaching a predetermined value under conditions of relatively high ambient scene light intensity thus automatically precipitating a fill-in flash mode of operation.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the mechanism and system possessing the construction, the combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.